”Parents

The assaults started Wednesday afternoon when the suspect followed two sisters, ages 7 and 12, as they were walking home from school, police said. He groped the younger sister’s buttocks and took off when the 12-year-old screamed, police said.

Just a few hours later, police said the assailant forced another 7-year-old to perform a sex act after she jumped over a fence to get a ball, police said.

Then on Thursday, the man exposed himself to a 13-year-old girl from a van and then trailed her for several blocks in South Ozone Park, police said.

All three crimes took place near 115th Street and Sutter Avenue in Queens.

City Council Speaker Christine Quinn and City Councilman Eric Ulrich urged residents Monday to come forward with any information that could help police.

“We simply cannot let the streets of Queens or anywhere else become places where girls and young women are unsafe,” Quinn said. “If this individual looks familiar and you’re hesitating picking up the phone, this victim was a 7-year-old girl — just remember that.”

Quinn: Queens Sex Assault Suspect ‘Will Be Arrested’

Police released new surveillance video on Saturday that shows the suspect walking away from one of the alleged incidents, police said.

“If you are the individual who has committed these crimes, you should turn yourself in now,” Quinn said Monday while holding up a wanted poster of the suspect. “The full force of the NYPD and the full force of the people of Queens County are looking for you and you will be arrested.”

A wanted poster for a sex assault suspect is seen in Queens on Sunday, May 5, 2013 (credit: CBS 2)

The NYPD has set up a command center as a makeshift precinct and officers have been going door-to-door with posters.

“There are eight additional patrol cars in the 106th Precinct alone. In addition, there are special investigators from the sex crimes unit assigned from downtown,” Ulrich said.

The search has also intensified with officers stationed at nearby schools.

Many parents in the neighborhood are desperate for an arrest.

“I got two kids, too, and I don’t want the same thing that happened to the girl to happen to my kids,” said parent Ivan Yagual.

“He’s just a psycho, that’s what he’s about,” said parent Mohammad Rauliff. “So we have to get rid of him.”

The suspect is believed to be in his 20s, around 6-foot, 160 pounds with black hair. He was last seen wearing a blue hooded sweatshirt with unknown white writing on the front, dark jeans and was carrying a purple backpack, police said.

A $12,000 reward is being offered for the arrest and indictment of the suspect.

Anyone with information is asked to call Crime Stoppers at 1-800-577-TIPS (5477). The public can also visit the Crime Stoppers website or text their tips to 274637 (CRIMES) then enter TIP577.